1. Field of the Invention
The present invention relates to a semiconductor laser module that provides a co-axial TO-CAN type package and transmission lines therein for complementary driving signal.
2. Related Prior Art
A conventional laser module having a co-axial shape is shown in FIG. 12. The laser module 60 includes a base 61, a block 62 on the base 61. A sub-mount 63 on which the laser diode 64 is mounted is disposed on the block 62. The base 61 further includes lead pins 65 and 66 electrically isolated from the base 61. One of lead pins 65 is connected to the anode electrode, which is formed on the top surface, of the laser diode 64 via the bonding wire 67. Another lead pin 66 is also connected to the anode electrode of the laser diode and grounded in the outside of the laser module 60. The base further includes the third lead pin 69 connected to the cathode electrode, which is formed on the bottom surface, of the laser diode 64 via the bonding wire 70 and the surface of the sub-mount 63.
Moreover, a signal for driving the laser diode 64 having a complementary mode is provided thereto just before the laser module 60 to balance the load characteristic for the complementary signal.
However, the conventional laser module shown in FIG. 12 has a significant gap between the tip of the lead pin and the electrode of the laser diode, which causes to increase the parasitic inductance when connecting therebetween by a bonding wire and degrades the high frequency performance of the laser module. Accordingly, one object of the present invention is to provide a laser module having a superior high frequency performance even in a co-axial type package.